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U.S. Department of Energy
Office of Scientific and Technical Information

Project Overcoat - An Exploration of Exterior Insulation Strategies for 1-1/2-Story Roof Applications in Cold Climates

Technical Report ·
DOI:https://doi.org/10.2172/1079099· OSTI ID:1079099
The development of an alternative method to interior-applied insulation strategies or exterior applied 'band-aids' such as heat tapes and ice belts may help reduce energy needs of millions of 1-1/2 story homes while reducing the risk of ice dam formation. A potential strategy for energy improvement of the roof is borrowed from new construction best practices: Here an 'overcoat' of a continuous air, moisture, and thermal barrier is applied on the outside of the roof structure for improved overall performance. The continuous insulation of this approach facilitates a reduction in thermal bridging which could further reduce energy consumption and bring existing homes closer to meeting the Building America goals for energy reduction. Research favors an exterior approach to deep energy retrofits and ice dam prevention in existing homes. The greatest amount of research focuses on whole house deep energy retrofits leaving a void in roof-only applications. The research is also void of data supporting the hygrothermal performance, durability, constructability, and cost of roof-only exterior overcoat strategies. Yet, contractors interviewed for this report indicate an understanding that exterior approaches are most promising for mitigating ice dams and energy loss and are able to sell these strategies to homeowners.
Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy Building Technologies Program
DOE Contract Number:
AC36-08GO28308
OSTI ID:
1079099
Report Number(s):
NREL/SR-5500-56145; DOE/GO-102013-3751; KNDJ-0-40338-00
Country of Publication:
United States
Language:
English